I build a few breadboard power adapter. Two small one, just connect the power from a wall adapter --> wall wart and a 5V regulator adapter with a reset circuit built-in with option Vin, 5V, gnd ---> check the jumpers.

I did try that wall wart...from Sayal and cost me under $3.00 ca CrossRoads. I put a dummy load ( 220 ohms ) and the voltage get lower ( around 4.75 V ) and at no load ( around 5.5 V ) ... Not to good in my opinion. But you notice my first picture ( the two small PCB breadboard adapter ), it is design to use a wall wart, even the 5 V, and other PSU ( rectifier and big cap ) <-- the one you need to screw the wire in. I made those adapter too.

I just finish an another DIY breadboard power adapter. This one is design to use a dual power supply, + / - and another + side. And it got switches to turn ON or OFF. It fit the breadboard power line, it have on each line a 0.1 uF and a 10 uF cap. The switches can from harvested e-garbage.